Scope: Recent studies have reported that tiliroside, a glycosidic flavonoid, possesses anti-diabetic activities. In the present study, we investigated the effects of tiliroside on carbohydrate digestion and absorption in the gastrointestinal tract.
Methods and results: This study showed that tiliroside inhibits pancreatic α-amylase (IC₅₀ = 0.28 mM) in vitro. Tiliroside was found as a noncompetitive inhibitor of α-amylase with K(i) values of 84.2 μM. In male ICR mice, the increase in postprandial plasma glucose levels was significantly suppressed in the tiliroside-administered group. Tiliroside treatment also suppressed hyperinsulinemia after starch administration. Tiliroside administration inhibited the increase of plasma glucose levels in an oral glucose tolerance test, but not in an intraperitoneal glucose tolerance test. In human intestinal Caco-2 cells, the addition of tiliroside caused a significant dose-dependent inhibition of glucose uptake. The inhibitory effects of both sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) inhibitors (phlorizin and phloretin, respectively) on glucose uptake were significantly inhibited in the presence of tiliroside, suggesting that tiliroside inhibited glucose uptake mediated by both SGLT1 and GLUT2.
Conclusion: These findings indicate that the anti-diabetic effects of tiliroside are at least partially mediated through inhibitory effects on carbohydrate digestion and glucose uptake in the gastrointestinal tract.
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